N.V. Singh

Genetic diversity and association mapping of bacterial blight and other horticulturally important traits with microsatellite markers in pomegranate from India

AbstractThis genetic diversity study aimed to estimate the population structure and explore the use of association mapping strategies to identify linked markers for bacterial resistance, growth and fruit quality in pomegranate collections from India. In total, 88 accessions including 37 cultivated types were investigated. A total of 112 alleles were amplified by use of 44 publicly available microsatellites for estimating molecular genetic diversity and population structure. Neighbor-joining analysis, model-based population structure and principal component analysis corroborated the genetic relationships among wild-type and cultivated pomegranate collections from India. Our study placed all 88 germplasm into four clusters. We identified a cultivated clade of pomegranates in close proximity to Daru types of wild-type pomegranates that grow naturally near the foothills of the Himalayas. Admixture analysis sorted various lineages of cultivated pomegranates to their respective ancestral forms. We identified four linked markers for fruit weight, titratable acidity and bacterial blight severity. PGCT001 was found associated with both fruit weight and bacterial blight, and the association with fruit weight during both seasons analyzed was significant after Bonferroni correction. This research demonstrates effectiveness of microsatellites to resolve population structure among the wild and cultivar collection of pomegranates and future use for association mapping studies.

A novel method of propagation in pomegranate: Mound layering

The experiment was conducted to elucidate the effects of different spacings on regeneration of stool shoots in pomegranate (Punica granatum L.). The report may be the first experiment based documentation of pomegranate propagation through mound layering. Plant height (cm), rooting percentage (%), length of longest root, number of roots per plant, average root length (cm), number of total and rooted shoots per plant, per m2 and per plot (3 x 2 m) were recorded. The results suggest that the performance of stool shoots were significantly influenced by spacing between mother stocks. The total shoot production per plot and per m2 (217.25 and 36.37, respectively) and rooted shoot production per plot and per m2 (117.15 and 19.51, respectively) were found significantly higher at the spacing of 0.5 x 0.5 m. The rooting of stool shoots found increased from 55.50 to 70.95% with the increase in spacing from 0.5 x 0.5 m to 1 x 1 m.

Biochemical profiling in pomegranate (Punica granatum L.) cultivar ‘Bhagawa’

The investigation on biochemical profiling in pomegranate cultivar ‘Bhagawa’ was carried out at experimental orchards located at ICAR-NRCP, Solapur. Fruit size, total soluble solids, pH, titratable acidity, total phenolics, total and reducing sugars, total anthocyanin and ascorbic acid contents were measured at various fruit developmental stages. Significant increase in total soluble solids, sugar content, total anthocyanins and ascorbic acid was observed, however, there was significant decrease in total phenolic content and titratable acidityas the fruits advanced to maturity (MS1 to MS5 stage).The ratio of TSS/TA is an important factor for deciding fruit maturity. Moreover, the significant increase in TSS/TA ratio from second to third and fourth to fifth maturity stages (MS2 to MS3 and MS4 to MS5) was observed due to increment in TSS and decrement in titratable acidity. A correlation matrix revealed significantly (P<0.05) strong relationships among almost all the parameters assessed. TSS showed positive correlationwith pH (0.682) and strong negative correlation (r =-0.882) with TA. TSS was also found to be strongly correlated with total sugars, reducing sugars and anthocyanins. Though, total phenolic contentwas negatively correlated with other variables except titratable acidity. Therefore, right proportions of these biochemical constituents could serve as reliable maturity markers to determine optimum fruit quality and fruit readiness for harvest.

Thermal requirement of pomegranate varieties growing in Maharashtra

A field experiment was carried out to quantify growing degree days (GDD) requirement of 10 pomegranate varieties (i.e. Bhagwa, Ganesh, Mridula, Arkata, Jyoti, G-137, P-13, Kandhari, Bassein Seedless and Jalore Seedless) at ICAR-NRCP, Solapur, situated at 17° 10’’ north latitude, 74° 42’’ east longitude and 483.5 m above mean sea level. The water requirement through drip irrigation system at 90% efficiency for Mrig bahar (rainy season flowering) ranged from 5.7–13.0, 8.0–18.2, 9.2–20.8 and 10.3–23.4 l day−1 tree−1 for 2nd to 5th year pomegranate trees. The seasonal values of water applied to 2nd to 5th year pomegranate trees were estimated as 1259, 1763, 2015 and 2266 l bahar−1 tree−1, respectively. Total GDD accumulations of all the varieties ranged from 2948 to 4105°D from defoliation to harvesting period. The growing degree days ranged from 947 to 1278°D at flowering stage and 2134 to 3306°D at fruiting stage. The lowest and highest GDD build up from defoliation to harvesting period were 2948°D for ‘G-137’ and 4105°D for ‘Bhagawa’, respectively. Photo-thermal index (PTI) at flowering and fruiting stages and heat use efficiency (HUE) of ten varieties ranged from 16.6 to 17.4°D/day, 16.5 to 18.3°D/day and 3.2 to 4.0 kgha−1 degree day−1, respectively. The growing degree days (°D), photo-thermal index and heat use efficiency indices may be used to assess the crop performance with respect to suitability of the variety to a particular locality depending on the prevailing thermal environment.